In the case of Marpmann, who found a dead Acarid in the urine of a man suffering from chronic nephritis, and in whom later examinations proved negative, the author himself was of opinion that the mite had reached the urine from outside.
We are certainly acquainted with mites living endoparasitically, namely, the Cysticolæ, Analgesinæ, of which Laminosioptes gallinarum live in the intramuscular and subcutaneous connective tissue of fowls, and Cytoleichus sarcoptoïdes in their air sacs. Another kind of mite (Halarachne halichœri) is occasionally found in the nasal mucous membrane of the seal (Halichœrus grypus), and, quite recently, Pneumonyssus simicola, which is more nearly related to Halarachne, has been found in the lung of Cynocephalus sp. It is therefore not improbable that endoparasitic mites are found in man; but no definite discovery has yet been made.
Family. Eupodidæ.
Small tracheate mites, with moderately long or short pedipalpi, composed of four segments, of which the last segments bend; cheliceræ forceps-shaped, with serrated edges; legs with two claws, more rarely with one, and terminating in a tuft ornamented with fine hairs; genital orifices on the abdomen, surrounded by a circle of little hairs. Most species live free—one lives parasitically on the bodies of slugs.
Genus. Tydeus, Koch.
Tydeus molestus, Moniez, 1889.
Fig. 356.—Tydeus molestus: seen in profile. Enlarged. (After Moniez.)
Male, 0·2 mm. in length, 0·125 mm. in breadth. Females, 0·225 mm. in length, 0·135 mm. in breadth; gravid female 0·315 to 0·360 mm. in length and 0·180 mm. in breadth. They were observed by Moniez on an estate in Belgium, whither the creature had apparently been imported twenty-five years previously with Peruvian guano; they appeared regularly in the summer and remained until the first frost set in; they were found on grass-plots, on trees and bushes in masses; they regularly attacked human beings, mammals and birds, tormenting their hosts in a terrible manner.